New York City commuters were recently treated to a surprise a capella performance by Michael Buble at a subway station on 66th Street at Lincoln Center.

The 37-year-old Grammy-winning Canadian crooner and the vocal group Naturally 7 sang the song "Who's Lovin' You." The track was written by Smokey Robinson and made famous by the Jackson 5 in 1969. It is featured on Buble's new album "To Be Loved," which was released earlier this week and features Naturally 7.

A video of their impromptu subway station performance with Buble was posted on his official YouTube page (watch it below).

Dozens of commuters, mostly women, filmed the gig on their cell phones. Others are seen exiting a train several feet away from Buble and Naturally 7. Several passengers smiled as they stepped onto the platform. One woman wearing sunglasses and listening to her own music with earphones showed no expression.

"I feel like a real New Yorker now," Buble said in the video, imitating a New York City accent.

He also said that singing in the New York City subway is "the most authentic, organic way to make music," adding: "You see some of the greatest musicians in the world come down here and play. Out of all the press I had to do, out of everything that I'm going to do in Europe and America, this was the thing I was most excited about."

Buble is set to perform in the United Kingdom and Ireland, starting on June 30. Naturally 7 is joining him on tour.

Michael Buble - Reese Witherspon duet

Buble's new album was released in the United States on April 23 and contains the song "Who's Lovin' You" as well as a duet with Reese Witherspoon. They sing "Somethin' Stupid," made famous in the 1960s by Frank Sinatra and daughter, Nancy Sinatra. The song has also been covered by Robbie Williams and Nicole Kidman in 2011.

Bubble told Rolling Stone in an interview posted earlier this week that he had initially thought about recording the track with a pop star, such as Katy Perry or Lady Gaga and that his manager had suggested Reese Witherspoon. The actress had won an Oscar for playing singer June Carter, wife of Johnny Cash, in the 2005 movie "Walk The Line."

"We love Johnny Cash, we loved 'Walk the Line,' and we loved her in that," Buble told Rolling Stone. "And both of us had huge crushes on her."